Method and apparatus for electrical treatment of gases



L. BRADLEY. H METHOD AND APPARATUS FOR ELECTRICAL TREATMENT OF GASES.

APPLICATION FILED JUNEZI, I916.

Patented Feb. 3, 1920.

4 SHEETS-SHEET 1- $1 Linn Brae/7e vi My p. MW A L. BRADLEY.

METHOD AND APPARATUS FOR ELECTRICAL'TREATMENT 0F GASES.

APPLICATION FILED JUNE 21,1916.

1,329,825. Patented Feb. 3,1920.

4 SHEETSSHEET 2.

L. BRADLEY. METHOD AND APPARATUS FOR ELECTRICAL TREATMENT OF GASES.

APPLICATION FILED JUNE 21. I916- Patented Feb; 3, T920.

1/11 6020 r: Z in Brad/ v rmy/2 0 L. BRADLEY. METHODAND APPARATUS FOR ELECTRICAL TREATMENT OF GASES.

APPLICATION FILED JUNEZI, I916- Patented Feb. 3, 1920.

4 SHEETSSHET 4.

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Lin Brae/fey h y A an @Hoznew UNITED STATES PATENT OFFICE.

LINN BRADLEY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO RESEARCH CORPORA TION, OF NEW YORK. N. Y., A CORPORATION OF NEW YORK.

METHOD AND APPARATUS FOR ELECTRICAL TREATMENT OF GASES.

Application filed June 21,

To all whom it may concern:

Be it known that I, LINN BRADLEY, a citizen of the United States, residing at East Orange, in the county of Essex, State of New Jersey, have invented a new and useful Method and Apparatus for Electrical Treatment of Gases, of which the following is a specification.

This invention relates to an apparatus for electrical treatment of gases, for example, for precipitating suspended particles from such gases by the action of an electrical field,- through which the gases are passed. In the treatment of gases coming from furnaces or similar apparatus, to remove dust or fume therefrom or for other purposes, considerable difficulty has been encountered on account of the tendency of the gas under certain conditions to present unsatisfactory conductivity, either by reason of the variations in temperature or.the variations in composition, from what is required for satis factory operation. Thus. I have found that under certain conditions the gas will not permit the production of a satisfactory discharge therein in such manner as to provide for effective electrical precipitation, and in some cases, either by reason of the variations in temperature in the flues or chambers of the precipitating apparatus. or by reason of variation in the composition of the gas, it isnot practicable to increase the difference of potential between the electrodes sufiiciently to produce the required silent discharge, for the reason that disruptive discharge will take place before the required amount of silent discharge is provided.

The main object of the present invention is to eliminate these difficulties by providing for a proper conductive condition of the gas being treated, and by further providing for uniformity of such condition throughout the precipitating apparatus. To this end, the present invention. provides for modifying or controlling the composition of the gas passing to the precipitating apparatus, in

such manner as to produce the proper con '(luctive condition therein, for example, by properly humidifying such gas; and the present invention further provides for maintaining uniformity of the condition of the gas during the precipitating operation, by excluding entrance of any outside air which might otherwise'enter the body of Specification of Letters Patent.

Patented Feb. 3, 1920.

1916. Serial No. 105,015.

gas passing through the precipitating apparatus by reason of leakage through the walls of the fines of such apparatus, for example.

An important feature of the, invention inthis connection is a provision for maintaining the body of gas passing through the pre cipitating apparatus under a condition of sufficient pressure to insure that leakage cannot take place from the outside air into such body of gas.

Another object of the present invention is to provide for uniformity of flow through a multiplicity of fines in the precipitating apparatus, this object being attained by making the' several fines substantially inde pendent and so constricting or obstructing the communication between the several fines and the manifolds or headers to which they are connected, that any local currents tending to be set up between adjacent fines are prevented or reduced by such constriction.

Another object of the present invention is to provide improved means for maintaining uniform temperature throughout all the flues or multiplicity of flues in the precipitating apparatus.

A further object of the invention is to provide, in connection with a precipitating apparatus having a plurality of collecting electrodes and a plurality of discharge electrodes mounted opposite the collecting elec-' trodes, improved means for suspension and insulation of such discharge electrodes, in such manner as to provide for maximum leakage resistance in the insulating supports for such discharge electrodes.

The accompanying drawings illustrate embodiments of my invention, and, referring thereto Figure 1 is a partly sectional diagrammatic plan view of the system of apparatus adapted for carrying out my invention.

Fig. 2 is a vertical section of one of the treaters or precipitating apparatus formlng a part thereof.

further modifications of the invention.

Figs. 18 and 18* are detail views of adjustable supports for the discharge electrodes.

Fig. 19 is a vertical section of a further modification, on line 1919 of Fig. 20.

Fig. 20 is a section on line 202O in Fig. 19.

Fig. 21 is a vertical section showing a difi'erent form of the gas-distributing means between the header and flues.

Fig. 22 is a section on line 22-22 in Fig. 21.

Fig. 23 is a vertical section of another modification.

The general plan of the apparatus is shown in Fig. 1, wherein a furnace 1, or other apparatus producing fume, or gas can rying dust or mist, is connected by flue 2, provided with damper 3, to a trunk or main 4, from which the gas is forced by a fan or blower 22, through pipe 22 and injector nozzle 2 to a header 5. From said header, inlet means 6, provided with valves 7 lead to the electrical treaters or precipitating means 8. Said treater-s may be of any suitable type, but are herein shown as of the vertical multiple pipe form, the gas passing. for example, downwardly in these treaters 8. The outlet means 9 for said treaters may be provided with dampers or valves 10 and are connected to a header 11. Said header 11 is connected by conduits 12, having dampers or valves 13, to treaters or electrical precipitators 14, whose outlet means 15, provided with dampers 16, are connected to header 17. The treaters 14 may be similar to treaters 8, but may be so connected to the headers 11 and 17 that the gas will flow upwardly therethrough. Header 17 is connected through damper means 18 to flue 19 leading, for example, to stack 20. A gate 21 may be provided between flue 4 and header 5, to permit direct passage of gas from said flue to said header, and in that case the jet of gas forced by blower 22- through nozzle 22", operates to boost or inject the gas into the header 5 so as to maintain a condition of pressure in the treater or treater. The 't'urnace may be provided with suitable devices for producing the pressure effect desired in the treaters. At any suitable point in the flue system. leading to the treaters, for example, in the flue 4, means 23 are preferably provided for spraying, or injecting or distributing water or steam into the gas. said means serving to humidity the gas, and also, if desired, to boost or force the gas forwardly to the treater, by injector action. The treaters and the supply and outlet con nections thereof, are so constructed as to nseaeaa substantially prevent entrance of outside air to the gas passing through the treaters, but as absolute air-tightness is not practicable, it is desirable, in some cases, to maintain a condition of pressure throughout the treater and its connections, and this is provided for by the blower and injector means above described.

Referring to Figs. 2 to 4, the treater is therein shown as adapted for use as one of the down flow treater-s 8, it being understood that it may be used as one of the up flow treaters 14, by interchanging the inlet and outlet connections. Said treater comprises, for example, a multiplicity of vertical flues or pipes 24, which, for the sake of compactness, may be made as square or rectangular pipes arranged in a plurality of rows, or they may be round or of any other shape. The inlet header 5 may extend alongside the plurality of rows of pipes, and communicate through gates or damper devices 7 with spaces between such rows, said spaces being closed at bottom by horizontal partition 26 which divides the space between the rows of pipes into upper and lower flue spaces 25, 25, so that such spaces are utilized for distributin thegas to the pipes. The lower spaces 25 open at their lower ends into a header or chamber 27 at the bottom of the treater, the pipes or fines 24: also opening at their lower ends into chamber 27 so that thegas may flow from said flues down into chamber 27 and then up through spaces 25. Pipes or flues 24 may extend up to the top plate 28 of the feeder, each pipe be ing closed at its top by said top plate, and having a lateral inlet 29 near its top from. one of the flue spaces 25. Each inlet 29 is preferably of smaller area than the cross section of the corresponding pipe or flue 21, .so as to provide constrictive resistance to the flow of gas through the pipes, and the amount of this resistance may be controlled by damper or gate means 30 at said inlets. All the flue spaces communicate with the i ilet header 5 extending alongside the rows of pipes or flues 24.

Suitable discharge electrodes 31 are provided in the respective pipes or fines 24, the latter serving as collecting electrodes. Said discharge electrodes may consist, for example, of wires. chains or other members hung -from suitable supports at. their upper ends and provided with means at their lower ends for holding them in position. In order to provide for most effective insulation of these discharge electrodes, I may support them at their upper ends by insulators 32 which preferably consist of elongated insulating rods 01- tu-bes of relatively small cross section, so as to reduce to a minimum the leakage along the surface of such insulators. Said rods or tubes may be hung from the top member 28 of the treater and the electrodes 31 may be hung from the lower ends of these insulators. Said insulators may consist of silica, serpentine, or

other material of high resistance and not subject'to. deterioration under the tempera-. ture and gas conditions present in the apparatus. With the described construction of electrode support, I prefer to provide means for supplying electric current to said electrodes at their lower ends, said means comprising, for example, a conductor 35 extending through an insulator 36 inthe top member 28 and down through one of the pipes or fiues 24, anct constituting, for example, one of the discharge electrodes, said conductor being connected at its lower end to a spacing frame 37 of conducting material whi'ch is also inconnection with all of the electrodes 31. Said electrodes 31 and conductor 35 pass freely through the spacing frame 37 and are provided with tensioning means such as weights 381 at their lower ends. Said spacing frame may be supported by resting on certain of said weights, for example, those at the four corners of the system of electrodes, and may be anchored by insulating anchor members or strain insulators 39 extending in differ ent directions to hold the spacing means from displacement in any direction.

Suitable means such as hammer levers 4L0 may be mounted in the spaces 25 and 25, on shafts 41 operated by means l2, so as to knockofl' the material collected on the walls of the pipes or fiues, said material falling into bins or hoppers 13, from which it is removed by suitable means such as discharge gates 44, 4A.

The discharge electrodes 31 are connected by wire 45 to any suitable electric circuit for supplying high tension current, either unidirectional or alternating, thereto, in order to produce an electric field between said electrodes and the walls of fines, pipes or electrode members 24:.

In the operation of the above described apparatus the gas is forced from the flue 2 by the action of blower 22 and of the injector means, so as to enter the treater 8 under a condition of pressure, and sufficient moisture or humidifying agent is supplied by means 23 to produce the requisite conductivity in the gas. I have found that in some cases it is necessary to provide the gas with water vapor or to humidify the gas in order to enable sufficient discharge to be produced for electrical action on the gas for precipitating suspended particles therefrom or for other purposes, at potential differences that can be maintained without disruptive discharge. In some cases, especially Where the gases already contain water vapor, such humidification is not necessary. In any case, however, it is desirable to maintain the temperature and composition of the gas fairly uniform after it has once been brought to good conducting condition, this object being secured by maintaining the apparatus under pressure so as to prevent leakage of cold outside air into .the apparatus, and by thermally insulating the gas While it is passing through the treaters, so that its heat will be retained. This thermal insulation is effected by the construction shown in Figs. 2 to 4, whereby the gas ings 29, or by suitably closing said openings by gate means 30, the fiow of gas is constricted at these points in such manner as to produce a resistance head which is in excess of the differences of pressure liable to exist in different fiues, so that any tendency to variation of flow in the different fiues is reduced or minimized by this continual resistance head. Moreover, the constrictive, openings being distributed laterally of the path of the gas and of the plurality of fiues, ,any tendency to in creased flow in any one of the fines will result in disproportionate increase in the adjacent constricting means, on account of the frictional resistance increasing substan tially as the square of the velocity, so as to effect a further equalization. of the flow in the different fiues.

The regulation of gas distribution by constrictive resistance of the inlet or outlet opening of each pipe may be carried out by simply making the openings 29 smaller than the cross section of the pipes, so as to produce a localized resistance to the flow, and the dampers for such openings may be omitted as illustrated in Figs. 5 and 6.

The supply of the gas under pressure to the treater is further of advantage in connection with this principle of control of gas distribution by constriction, as it enables a greater amount of constrictive resistance orresistance head to be used, and it also facilitates the use of down flow in the fiues as in treaters 8.

A serious difliculty in the operation of gas treaters .of the type herein shown is the tendency of the gas to flow unequally in the different fiues, by reason of differences in temperature in different fiues, or for other reasons, and in same cases the gas may even be drawn down some of the fiues by reason of the greater buoyancy of the gas in adj acent fiues. These difliculties' are avoided by closing the direct communication at the top of the fiues, between adjacent fiues, so as to shut off such local circulations, and by constricting the passage of gas between the fines and the headers, as above described. The provision for down flow in treaters 8 is also of advantage in this connection, as it provides for a certain amount of automatic equalization, for the reason that there is a continual tendency to cooling of the gas in traversing the fines and any tendency to excessive velocity of the hot gas in any flue will tend to keep the gas in such flue warmer, and increase its buoyancy relatively to the gas in the other fines, so as to tend to equalize the flow. For this reason the agglomeration and precipitation of the particles is, in general, most advantageously carried out in a down flow treater. It is, however, desirable in some cases to follow the action of a down flow treater by an up flow treater, as shown, for the reason that the latter, having its outlet'farthest removed from the collecting bins at the bottom, enables the finer particles to be more effectively separated.

In case the gas being treated is of insufficient conductivity to provide the proper electrical discharge for eifective precipitation, its conductivity may be increased by supplying steam or water vapor thereto, either by admitting steam at means 23 in flue 4 or elsewhere in the path of the current of gas, or by admitting water at such point and causing such water to be evaporated by the heat of the gas. In treating smoke or gas containing soot or similar -material which is so light and non-coherent that it .will not remainprecipitated or vwill not fall by gravity to the collecting bins, water may be supplied by the means 23, for example, to wet the smoke or suspended matter so as to cause the particles to cohere, when precipitated, into a mass of sufficient weight and cohesion to remain deposited and to slide or fall into the collecting means at the bottom of the fines.

In place of steam, or. water for controlling the conductivity of the gas I may use any other agent capable of. producing proper conductivity in the gas being treated, for example, sulfuric acid "apor may be used in some cases. By conductivity I mean the capability of transferring electrical energy from one electrode to the other, through the intervening gases, and by controlling the conductivity, I mean afl'ecting any one or all of the factors entering into the con ductance of electricity through gases, especially when such gases contain suspended liquid or solid particles, including, among such factors, the discharge or transfer of electricity from the electrodes into the gases.

The discharge gates 44' and 44 are arretirees ranged respectively at the top and bottom of chambers 134 at the bottom of bins 43, said gates being operated by levers and 135 so as to first open gates 44, allowing the collected material to fall into said chamber, and to then operate the gates 44 to discharge the material from the chamber. An air vent pipe 136 extends from the chamber 134 upwardly into the bin space, so as to vertical lines or pipes 50, are also spaced apart vertically and communicate with the respective headers 46 and 47 through constricting gates 51 and 52. Further constricting means may be provided between the lower chambers 49 and the chamber 53 at the bottom of all the fiues, said constricting means consisting, for example, of dampers 01 valves 54 adapted to close, to any desired extent, openings 55 in the top of said chamber The construction of the discharge electrode system, indicated at 57 may be as above described with reference to Figs. 2 to 4, the spacing frame 58 being, however, in this case, shown as anchored by a conductor 56, passing through a sleeve insulator 56 and serving to conduct current to the dis charge electrode system.

Instead of constricting the passage of gas to 01' from the fiues or pipes by means of a contracted opening in the side wall thereof, I may provide any other suitable constricting means. For example, as shown in Fig. 9, the upper header 59 may extend above the vertical flues or pipes 60, and a cap 61 may extend over each pipe, formed of a wire screen, or cloth, or other fora-minous material adapted to permit passage of the gas with sufiicient friction for the stated purpose. Or, as shown in Fig. 10, the constrictmg devices, indicated at 63, maybe formed as tubular screens extending between the top of the pipes or fiues 64 and the top of the header 65. In some cases, as shown in Fig. 14, a foraminous screen'63 of suitable insulating fabric, such as open weave cotton cloth, may be stretched across the top of each pipe or flue 64', extending over the space between the wall of said pipe and the central electrode 62 which is hung from an insulated support 62. I have found that, in some applications of the invention, the insulation presented by such a construction is suflicient for the purpose. The constricting action may also be secured by contracting the upper ends of the pipes or fiues, as shown at 66in Fig. 11, the space at the top of the pipe being further contracted by the insulators 67 for the discharge electrodes 68'. A

plate or spider may be placed over the pipes 69, as shown at 7 0 in'F'ig. 12, said plate also serving for support of the insulators 71 on which are hung the discharge electrodes 72. As shown in Fig. 13, domes or caps 73 may be placed over the pipes or fiumes 74 and.

provided with constricting openings 75, said domes or caps also serving to support the in sulators 7 6 for discharge electrodes 7 '1' The constriction may, if desired, be provided at the bottom of the fines or pipes as shown, for example, in Fig. 15, where the header 80, which may be either an inlet or outlet header, communicates with the flues or pipes 81 through constricting openings 82. I have in this case shown the discharge electrodes-83 as held at tlieiiwlower ends by tubular insulators 84 of considerable length ing 0 V enings 98 and and small diameter, a conductor 85. being connected to said electrodes and passing through an insulating sleeve 86 in the wall of the lower chamber 87. Said insulators 84 are mounted in spiders 88 which extend across the lower ends of pipes or fines 81 in such manner as to permit the precipitated material to fall through to the chamber 87 The construction shown in Fig. 16 is similar to that of Fig. 15 except that the spider 88 is located above the openings 82', so that the gas passing through the fines or pipes 81 has to pass through the openings in said spiders.

As shown in Fig. 17, the flues or pipes indicated at 24' may have outlet openings 29' opening from one flue to another so that the gas eventually reaches the header 11 extending alongside the outermost row of fines. lVith this construction the fines may be arranged in close order without requiring intervening spaces. The openings 29 are preferably of such dimensions as to provide for constriction of the gas, the openings being larger in the case of the fiues nearer the outlet header, to provide for passage of gas coming from the interior flues.

Fig. 18 illustrates the application of the gas control by constriction to pipes or fiues 90 which opendirectly into lower and upper headers 91 and 92. The inlet and outlet flues 93 and 94 extend alongside the pipes or flues and communicate with spaces 95 and 95 around said flues, said spaces being inclosed by a casing 96 and separated by a partition 97. These spaces 95 and 95 communicate respectively with the upper and lower headers 91 and 92 through constrict- 98 in the top and bottom eader plates. Deflectors 99 may be placed adjacent to said openings to prevent the gas from passing through the openings with a jet action which would tend to produce objectionable currents in- .the headers.

,7 mounted on an insulated frame 100 in the upper header, the electric connection for supply of current being made to this frame. Except as described, the construction may be similar to that of Fig. 2. The mounting of the discharge electrodes on the frame 100 is preferably adjustable to enable said electrodesto be centered in the pipes. For this purpose, as shown in Figs. 18" and 18*, each electrode may be hung from a clip 148 bolted to the frame100, slots 100, 148 being provided in the frame 100' and in the clip 148 respectively to enable adjustment of the clip in either direction ina horizontal plane.

Fig. 19 shows a construction similar to that of Fig. 18 as regards the connection of the inlet .and outlet flues to the treater fines. Flue 101, which may, for example, be the inlet flue, opens into a chamber 101 in a casing 106, and the other flue 102 opens into a chamber 102, in said casing, these chambers being separated by a horizontal partition 108, and being provided respectively with top and bottom plates 104 and 105 through which they communicate respectively with a top chamber 109 and a bottom chamber or bin 110. .The treater fiues or pipes 103 are shown as separated pipes extending through chambers 101' and 102 and into the respective chambers 109 and 110. Plates 104 and 105 are provided with constricting passages 104 and 105 distributed between the flues ,103 to equalize and regulate the flow of gas. Discharge electrodes 111 are here shown as wires suspended from a frame 140 extending into insulators 142 in chambers 140. These insulators may be protected by hoods 142 to prevent deposition of dust, etc., thereon. Wherever there is liability of sparking or arcing between the high potential and grounded parts of the apparatus, I prefer to provide rounded surfaces as indicated at the ends 150 and 150" of the treater pipes in Figs. 18 and 19. The parts of the frame 140 whichpass through the openings in the header walls into the chambers 141 are likewise protected by sleeves 144 which extend around said frame portions, sleeves or thimbles 145 being also provided at the edges of said openings for the same purpose. The discharge electrodes maybe provided with enlargements or sleeves 146 for the same 1purpose, as shown in Figs. 7, 21 and 22 w ere they pass the ends of the fines or pipes.

In the above described embodiments of my invention I have shown means for controlling gas distribution in a plurality of pipes by interposing obstructing means in the path of the gas, and provided with constricting passages offering resistance to the giving access to these damper plates.

flow of gas so as to tend to maintain uniform velocity in all the difierent pipes or flues. In the forms of the invention shown in Figs. 1 to 17 these constricting passages are associated individually with the respective pipes or flues, whereas, in the forms shown in Figs. 18 to 20 the constricting passages or openings are located adjacent to the respective pipes or flues, but each con; stricting passage is in communication with more than one pipe or flue. Figs. 21 and 22 show a further modification of this same feature, in which the constricting passages or openings indicated at 113 and 114 are formed in plates 113 and 11% located respectively in the bottom and top headers 115 and 116 for the several pipes or fines 118. One of the headers, as for example the lower header 115, may connect one or more fiues 119 with a supply flue 120, said passage or passages 119 being provided, for example, with dampers 121. The other header 116 may be provided with outlet passages or fiues 123 leading to an outlet flue 124: and provided respectively with dampers 125. The passages or openings 113, 114 in the plates 113 and 114 are preferably smaller in cross-section than the pipe or fines 118 and may, for example, be located directly over and u'nder the respective flues 118, these openings or passages 113', 114: offering a constrictive resistance to the passage of gas therethrough so that excessive velocity of gas passing between the headers through any of the pipes or fiues 118 will encounter abnormal resistance at these constricting passages, and any tendency to abnormally high velocity through any of the pipes or flues will thereby be eliminated or reduced. In order to further equalize the flow in case there is a tendency to variation in flow such as cannot be overcome by the uniform constriction above described, 1 may provide for varying the amount of constriction, for example, by means of damper plates 127 adapted to close the openings 113', 114' more or less. Suitable means, such as man-holes 128, may be provided for In order to provide for the distribution and constrictive control of the gas flowing to the different pipes I may, as shown in Fig.

23, provide the obstructing plate 130 with passages 131 formed in the manner of Venturi tubes so as to permit the gas to flow through the same without undue generation of eddy currents and permit the gas to flow evenly and smoothly into the respective pipes. In other respects the construction may be as described in connection with Figs. 21 and 22, and in both of these treaters the support of the discharge electrodes may be substantially the same as described in connection with Figs. 18 to 20. The discharge electrodes 111 are shown in these figures as aaaeaa 'adjustably mounted on the supporting checking the velocity or reducing the kinetic energy of the gases while maintaining a smooth, uniform flow. The form of the invention shown in Figs. 21 to 23 is especially adapted to produce this effect, the constricting plate 113 in Fig. 21'or 130 in Fig. 23, with the opening or passage means therethrougli, serving to deliver the gas to the treater pipes or flues at reduced velocity and in uniform manner and to eliminate eddies and unequal distribution which would otherwise result from considerable change in velocity. It has been found that, in general practice, an increased as velocity through the constricted openings of from four to five times the velocity through the main part of the tubes or pipes, is ampie to insure uniform gas velocity, temperature and composition in the various tubes, it being found desirable to maintain such uniformity throughout the various tubes. Excessive temperature or gas velocity or non-conductive gas in one or a few tubes may give unsteady operating conditions.

The constricting efiect in some cases may be obtained by placing an iron rod or tube of suitable size and shape in place of the insulator as indicated at 66 and 67 in Fig. 11; but if the insulator is not used some such arrangement as indicated by 140, 142, 1&4, 145 in Fig. 19 may be used to advantage and still retain the. constriction features. By avoiding sharp edges or points where this constriction occurs, higher voltages are allowed. When these elongated insulators are used and dust or fume tends to collect and thus Weaken the insulation it may 'often be advantageous to pass the gases at liigh velocities adjacent these insulators thus de-- .either on or within the dielectric. Leaky insulators may generate sufiicient heat to sinter dust on their surfaces, or in some cases to evaporate liquids which otherwise porous tubular or rod type insulators are preferable toporous insulators as less leakage can take place and surges are less liable to be set up, since an unsteady resistance, such as a leaky insulator, promotes surging by sudden fluctuations in current. Likewise these insulators should be of such length tubes.

as to reducev current leakage to a minimum.

When water either as spray or as steam is introduced into a gas in order to increase conductivity or otherwise to improve operating conditions care should be. taken to insure getting the gas and moisture thoroughly mixed prior to reaching the electrodes.' Experience shows that an excess.

of moisture is far less detrimental than a slight insufliciency- In the treatment of gases from iron blast furnaces considerable potassium compounds have been found in the dust and as some of these are hygroscopic allowance must be made when endeavoring to so control temperatures as to keep insulators dry and non-conductive. Wherever feasible, insulation should be avoided at the point where the gas enters, especially if the collected dust tends to materially weaken the insulation. Swinging electrodes may be avoided by eliminating high gas velocities and eddies provided the discharge electrodes are held plumb by suitable weights and are uniformly spaced from collecting electrodes.

. sure drop across these constrictions the outside air can be excluded and at the same time insure uniform gas conditions in the various This uniformity permits treating the maximum amount of gas in each tube and allows. the minimum of power consump tion for a given volume of gas, and also the precipitator requires less space and costs less to install. I y

In some installations the draft loss permissible is very small and the fines and other gas passages must be so arranged and proportioned as to insure uniform conditions In some cases it is desirable to leave the in the precipitator tubes without requiring much draft energy. By avoiding sharp bends, high gas velocities, quick changes of gas velocity, and preventing large temperature changes, the draft loss can be kept very low. The gases should be introduced to the electrodes and conducted away in such manner that no zones of abnormal gas pressure (static or dynamic) are produced in any portion of the treating chamber. If this condition is maintained very little if any loss of draft can occur, and especially if the gas passages are so built as to retain the heat of the gases. Since even distribution of gases is so desirable, it is best to concentrate "the draft loss at a point where it can be the most effective, and this is found to be in some portion of each tube or other gaspassage whichcontains electrodes. The more care used to get gases uniformly and gradually introduced to the various tubes and the better the gas temperature is maintained constant throughout each tube, the less constriction or other means of producing resistance to gas. flow will be required to insure uniformity of conditions between the electrodes.

When dust or fume builds up on the discharge electrodes or collecting electrodes to a point where results are not satisfactory in'iprove-ment may be had by jarring the deposit from the electrode. In some cases the tubes, require rapping at more than one point and also these should be permitted to Vibrate a sufficient amount when the arrangement shown in Fig. 7 is used, each individtialtube or group of tubes may be shut off to prevent or reduce gas flow while the deposit is being removed, thus facilitating it to drop against the gas without suffering it to be carried away by moving gases.

When the gases to be treated would make an explosive mixture with air, it is highly desirable to keep the gases under pressure above that of the atmosphere so as to prevent even accidental leakage of air into the gas since explosion might occur if disruptive discharge took place between the electrodes.

Insulators having considerable surface should not be placed in a horizontal. position, especially when conductive fume ordust is collected as the more fume or dust collects on the insulator the greater is the current leakage and the more tendency there is for the insulator to become coated with a sintered or baked product, and for the insulator to crack due to thermal stresses. If the dust contains both conductive and non-conductive particles, there is a tendency for theconductive particles to line up in chains, due to the electric field, and this condition facilitates insulator failure; hence the neces- I vided the tubes remain vertical and the gas currents or eddies and the electrical forces are not strong enough to cause the discharge electrodes to swing as pendulums. Fastening the several discharge electrodes together at their lower ends by a spacing frame assists in keeping proper spacing and avoiding swinging, but the tubes themselves may be displaced from the vertical and cause trouble. I have found that by building for example the four corner tubes so that their longitudinal axes are at an appreciable angle from the vertical and not parallel with each other their discharge electrodes can hold the spacing framework in the lower gas chamber in any desired position and in turn the discharge electrodes in each other tube can be held in proper spacial relationship with its respective collecting electrodes by means of the spacing frame.

What I claim is 1. In the art of electrical treatment of gases the method of maintaining the operating conditions uniform in a plurality of treater flues in multiple arrangement which consists in substantially equalizing the pressure of the gases in the different flues.

2. Inthe art of electrical treatment of gases in a plurality of treater flues in multiple arrangement the step which consists in substantially equalizing the temperature of the gases in the different flues.

3. In the art of electrical treatment of gases in a plurality of treater flues in multiple arrangement, the step which consists substantially equalizing the dielectricin conditions of the gases in the difierent flues.

4. In the art of electrical treatment of gases, the method of maintaining the operating conditions uniform in a plurality of treater flues in multiple arrangement which consists in controlling the temperature and composition of the gases and the rate of gas flow in the diiferentzfiues.

5. In the art of electrical treatment of gases, the method of controlling the conductivity of such gases, which consists in supplying and distributing therein material adapted to vary-the conductivity thereof.

6. In the art of electrical treatment of gases, the method of increasing the conductivity of such gases, which consists in rsaaeee sation.

7. In the artof electrical treatment of I gases, the method of controlling the conductivity of such gases, which consists in supplying water vapor thereto and maintaining the. gases under a condition of temperature such as to maintain the conductivity thereof.

8. In apparatus for electrical treatment of gases, a treater chamber having a plurality of flues, and means for equalizing the conditions in the said flues including means for substantially equalizing the temperature of the gases in the different flues.

9. In apparatus for electrical treatment of gases, a treater. chamber having a plurality of flues, and means for equalizing the conditions in the said flues including means for substantially equalizing the dielectric conditions of the gases in the different flues.

10. Inapparatus for electrical treatment of gases, a treater chamber having a plurality of fines, and means for equalizing the conditions in the said flues comprising means for substantially equalizing the Pressure and temperature of the gases in the different flues.

11. In apparatus for electrical treatment of gases, a treater chamber having a plurality ef flues, and means for equalizing the inlet and an outlet, a plurality of treater flues in the chamber in multiple arrangement, and means for controlling the rate of gas flow through the different flues.

13. In apparatus for the electrical treatment of gases, a treater chamber having an inlet and outlet, a plurality ofitreater flues in the chamber in multiple arrangement, and adjustable means for regulating the rate of gas flow through the different flues.

14. In apparatus for the electrical treatment of gases, a treater chamber having an. inlet and outlet, a plurality of treater flues in the chamber in multiple arrangement, and adjustable constrictive means for regulating the rate of gas flow through the different flues.

15. In apparatus for the electrical treatment of gases, a treater chamber having an inlet and outlet, a plurality of treater flues in, the chamber in multiple arrangement, and adjustable constrictive means adjacent the admission end of said flues for regulating the rate of gas flow therethrough,

16. In apparatus for theelectrical treat ment of gases, a treater chamber having an in the chamber in multiple arrangement, and adjustable constrictive means adjacent the exit end of said flues for regulating the rate of gas flow therethrough.

17. In apparatus for electrical treatment of gases, a treater chamber having an inlet and an outlet, a plurality of treater flues in the chamberand means in the treater chamber constricting the flow of gas to produce a resistance head in excess of the variations of pressure in said treater chamber.

18. In apparatus for electrical treatment of gases, a treater chamber and a plurality of treater fiues therein, means in the chamber for constricting the gas flow to produce a resistance head and means for passing the gas through the chamber under such conditions of pressure as to substantially equalize the rate of-- gas flow through the diflerent flues. I

19. In apparatus for the electrical treatment of gases, the combination of a treater flue and means for passing the gases along the outer surface of the flue and then into the flue;

20. In apparatus for electrical treatment of gases, a treater having a plurality of treater flues and a manifold, and means for controlling the as fiowibetween the manifold and the diil erent flues; fr 21. In apparatus for electrical treatment of gases, a treater having a plurality of treater flues and a manifold, and adjustable constricting means for controlling the gas flow between the manifold and the different fiues. 22. In apparatus for electrical treatment 7 of gases, a treater having a plurality of treater flues, a gas retaining chamber surrounding said flues, and means for controlling the gas flow between the said retaining chamber and the different flues.

23. In an apparatus for electrical treatment of gases, a plurality of vertical treater flues, a gas retainin chamber surrounding the upper portion of the flues, a. gas retainingchamber surrounding the lower portion of the flues, the flues and the said chambers being so interconnected that the gases to be treated pass through one of the chambers into the flues and the cleaned gas from the flues through the other chamber.

24. In an apparatus for electrical treatment of gases, a plurality of vertical treater flues, a gas retainin chamber surrounding the upper portion 0 the flues, a gas retaining chamber surroundin the lower portion of the flues, the flues an the said chambers being so interconnected that the gasesto' be treated pass through one of the chambers into the flues and the cleaned gas from the flues through the other chamber, and means for controlling the gas flow through the difof gases, a plurality of vertical treater flues constricting means for controlling the gas flow between the difi'erent flues and the manifold through said openings.

27. In an apparatus for electrical treatment of gases, a plurality of vertical flues provided with electrode means, said flues being closed. at their upper ends, a lower header opening into the lower ends of said flues, and an upper header extending alongs1de the said flues, said flues having lateral openings communicating with said upper header.

28. In an apparatus for electrical treatment of gases, apluralit of vertical flues closed at their upper encs and having lateral openings, a lower header communicating with said lateral openings, and adjustable closure means for said openings.

29. In apparatus for electrical treatment of gases, a plurality of rows of flues separated from one" another to define gas passages, and means whereby gas is caused to pass through said passages and said flues in succession.

30. In apparatus for electrical treatment of gases, the combination of a plurality of vertical flues arranged so as to form spaces between said flues,'means for dividing said with the upper and lower portions of the flues so that the gas passes through said spaces and flues between the inlet and outlet means.

31. In apparatus for electrical treatment of gases, a plurality of treater flues in multiple arrangement, means for defining a gas passage transversely of said flues, and constricting communications between the said passage and the flues. I

32. In apparatus for electrical treatment of gases, a plurality of treater flues in multiple arrangement, means for defining a gas passage transversely of said flues and communicating therewith, and means for restricting the flow of gas through said flues.

' 33. In apparatus for electrical treatment of gases, a plurality of treater fluesin multiple arrangement, means for defining a gas passage transversely of said flues, and adjustable constricting, communications between the said passage and theflues.

34. In apparatus forielectrical treatment of gases, a plurality of treater flues in multiple arrangement havin openings in their walls, and means for de ning a gas passage transversely of the fines and in communication with said openings.

35. In apparatus for electrical treatment of gases, a plurality of treater flues in multiple arrangement having adjustable openings in their walls, and means for defining a gas passage transversely of the fines and in communication with said openings.

36. Apparatus for electrical treatment of gases comprising a row of vertical treater flues, having openings in their walls, means for defining a gas passage transversely of the fines and in communication with the:

said openings, a manifold adjacent the said gas passage, and means for controlling the flow of gas between the manifold andthe gas passage.

37. Apparatus for electrical treatment of gases, comprising a row of vertical treater flues, adjustable openings in the walls of the treater flues, means for defining a gas passage transversely of the flues and in communication with the said openings, a manifold adjacent the said gas passage, a means for controlling the flow of gas between the manifold and the gas passage.

38. Apparatus for electrical treatment of gases comprising a plurality of rows of vertical treater fiu'es spaced from each other to define gas passages, adjustable openings in the walls of the fines in communication with said passages, a manifold transversely of the said rows of flues and said passages,

and adjustable gates for controlling the flow gases comprising a plurality of rows of vertical treater flues spaced from each other to define gas passages, partitioning means for dividing said gas passages into upper and lower portions, a manifold in communication with the upper portions, a manifold in communication with the lower portions, openings in the walls of the treater flues communicatin with the upper and lower portions of the gas passages, adjustable gates for controlling the flow of gas between J one portion of the gas passages and the different treater fiues, and adjustable gates for controlling the flow of gas between one of the manifolds and the gas passages communicating therewith.

In testimony whereof I have hereunto set my hand, at New York, N. Y., this 20th day of June, 1916.

LINN BRADLEY. 

